Decomposers are animals that eat dead animals or carcasses. They play an important role in an ecosystem by helping break down carcasses. Fungi and bacteria are the main decomposers.

Actinomycetes
Actinomycetes, University of Guelph, Brief, all-text description of Actinomyctes.
Decomposers
Decomposers, NatureWorks, New Hampshire Public Television, Image Credits: Clipart.com unless otherwise noted, Images and information on bacteria, fungi, and earthworms; click on image for large
What is a Decomposer
What is a Decomposer, Qualitative Reasoning Group, Northwestern University, Information for younger students.